Domcomp - No-nonsense domain price comparisons, updated daily
namegrep - Domain name search with regular expressions and curated sets
Domainr - Domainr
CunningBot - Find best domain names
dofo.com - Domain search platform Dofo.com gathers all registered (350 million) domains of the world in a single place. Dofo also brings together all the domain names that are on sale, provides useful features, all completely free.
Agile Domain Search - Search great domain names for your website in seconds.